Deuce flasher box troubles.

I have an M35A2 that all the lights work on except the turn signals. I replaced the original flasher box on the truck with a used but working box. The turn signals worked, but only for about a month. During that month I only drove the truck for maybe 4 hours total. I thought that maybe the used flasher box was near it's end and I was happy to get some use out of it. I figured the best thing to do was to just buy a brand new flasher box. I did that, bolted it in and like magic....the turn signals worked again. I thought I was done with the signal problem.
The first time I drove the Deuce since replacing the box and the turn signals only worked for maybe 6 turns and stopped working again. Is there anyway that my wiring harness or something other than the box is causing the flasher box to short out?? The ground wire on the flasher box is clean and secure. Anyone else had a similar problem?? Thanks.

Mark

I'm having the same problem,hopefully someone here has a good idea.

If the turn signal lever on the steering column is not TIGHTLY secured to the column, it wont work either. That grounds the flasher. Try tightening it up.



It is definitely a ground issue somewhere.

Isn't there some kind of aftermarket upgrade we can do? I imagine if it was out there, someone would have done it by now though.

dm22630 said:

If the turn signal lever on the steering column is not TIGHTLY secured to the column, it wont work either. That grounds the flasher. Try tightening it up.



It is definitely a ground issue somewhere.

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The hose clamp for the turn signal switch only grounds the indicator light, the flasher unit is grounded via wire "C" on the box.

For a more reliable operation and to save the flasher unit in case of shorted circuits or overloads add a relay as shown here.
This subject has been covered many times before, do a search for all the info.

I need to go through all my grounds. I suspect that's why mine aren't working. I have some relays that I'm going to use to put in protect the unit.

I had the flasher issue as well and I did the cranetruck fix and no problems whatsoever. Its not a hard fix either.

Cranetruck,

Thank you for the info and drawing. I will put that all together and see what happens. Thanks to all the rest for your input so far.

Mark

What is the exact type of 25 amp relay that I am looking for? Brand, etc. I found the IN 4003 diode at Radio Shack. Where can I find the relay?

We had the same problem and we found the ground was no good, run a new ground wire. Then after we had the ground issue we found out that the flasher arm control on the steering column was the problem, we changed it and now problem gone. If you have a spare flasher control try changing it.

I'm using a 24 VDC 10 amp Allen Bradley relay. We use them at work so I grabbed a few that were laying around along with some bases. Any brand relay will do.

We had this problem on a deuce. We found that whoever put the light on the right fender had replaced the mudguard box under the fender and trapped a wire between the mudguard box and the fender. The wire insulation finally got squashed out enough to short the wire, and the a blown flasher was the result.
Regards Marti

M543A2 said:

..........The wire insulation finally got squashed out enough to short the wire, and the a blown flasher was the result.
Regards Marti

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If you have had one of the original solid state flasher units, this wouldn't happen, the breaker would have tripped. In the sixties, they were designed with a heavy duty SCR, which could handle shorted loads long enough to open the CB.
There may be some new designs out there with short circuit protection, but the flasher box isn't marked and apparently it's no longer a requirement, so the manufacturer happily supplies replacements.....

BTW, the relay mod causes the breaker to trip in case of a short. Just keep in mind that the "lamp load" is only a fraction of the normal relay contact rating (cold filament inrush current must be considered).

Can I get one of you guys to take a photo of your relay and diode additions to your flasher box? Bjorn, the drawing was helpful, but I a picture would be great. Thanks. Sorry guys...I really stink at electrical stuff.

Mark

Blinker trouble – Coincident???

My Deuce has been eating flashers; usually when a bulb burns out. Last time, I was in a hurry so I just connected the replacement flasher to the wiring harness and simply laid it on top of old flasher. Everything worked. And I promptly forgot about it. After several trips without incident, I remembered that I hadn’t mounted the flasher. I mount it and made sure I had a good ground. On my first trip out, it quits. Is this just a coincident? If it isn’t, could I protect my flasher by isolating it and grounding it through a fused ground while I try to find the actual cause of the problem? I’ve read the threads on splicing in a circuit breaker but I don’t have the knowledge to figure out the wiring diagrams and I really don’t want to cut my harness. I was planning on making a fused line using the end of an old harness and pieces from a failed flasher, but then I recalled the circumstances of my last failure and questioned whether or not a fused ground would work instead.
Thanks for any help. Ron

Ron, the new (made since 1980 or so) solid state flashers use a transistor to switch the load (light bulbs) and no fuse will react fast enough to protect it. Some may have internal short circuit protection, but there is no way to tell by the part number.

If you are lucky enough to find one of the original solid state flashers, made in the 1960s, you'd be safe, they were made to handle a direct short long enough for the circuit breaker in the light switch to trip, a heavy duty SCR did the switching then...

cranetruck said:

Ron, the new (made since 1980 or so) solid state flashers use a transistor to switch the load (light bulbs) and no fuse will react fast enough to protect it. Some may have internal short circuit protection, but there is no way to tell by the part number.

If you are lucky enough to find one of the original solid state flashers, made in the 1960s, you'd be safe, they were made to handle a direct short long enough for the circuit breaker in the light switch to trip, a heavy duty SCR did the switching then...

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Thanks. My first one looked just like the old version shown in a comparison post but it died after my second bulb burned out. I wasn't able to find another one so my last ones have been of the newer styles. I contacted the manufacturer of the latest version, but was told by them that the newest one were designed for the LED lights which is a lesser load and I should stick with the standard replacements i.e. the 1980ish ones. Thanks for saving me from so worthless work. Ron

Bjorn, I felt a little foolish today (as I readied the truck for the church to use to move a NG wife to a new home) - I noticed that the ground wire is part of the harness. So my thinking that a less than good ground had kept the old flasher from burning out was all wrong since it was grounded the whole time. If my new flasher burns outs, I'll just get someone who understands electrical circuits to build the set up in the diagrams. Thanks again for your help. Ron

interesting...I am having the same issues, I noticed that if I leave the flasher on for a while, the lights will be steady...then start to blink....after that, they seem to work fine...but is like they need to warm up or something before the lights will blink...

I am researching an aftermarket flasher right now...there are many of them avail but all just as expensive or more than the OEM military replacement. I will let you know how that goes.

My truck has a flasher module less than a year old in it and it will not work at all....Is there any way to test them?